Extreme and fluctuating weather conditions, including high humidity, below-freezing temperatures, and ice storms, can cause ice to form on power lines or conductors. Ice weight can put a lot of stress on power lines or conductors and damage equipment. In windy conditions, icy lines can whip violently and gallop, causing tie wires, tie assemblies, and other connections, to weaken and break, wood poles to snap, and even steel towers to crumple. Hoarfrost or snow, whilst lower in weight than ice and causes less strain on power lines or conductors, can quickly transform into ice under certain weather conditions which can pose even greater risk due to the element of surprise. Accordingly, removal of extraneous matters such as ice, hoarfrost, and snow, from power lines or conductors must be done as quickly as possible to prevent equipment breakage and loss of power. Without exception, strategic, timely, and safe, keeping power lines clean and free of extraneous matters are of extreme importance.
Although the importance of preventing build-up of extraneous matters on power lines has been universally recognized and acknowledged, the ramifications and immense cost implications of downed power lines due to same have become even greater priority concerns for the electrical industry in light of the increasing adverse weather systems and events across the globe.
In the industry, removal of ice from power lines is commonly done through ice melting and manual ice removal.
Melting is limited to use in certain specific situations on isolated circuits. Ice melting requires certain section of lines to be first de-energized. A controlled short-circuit is placed at one end of the line, and the current flow creates a momentary jolt and temperature increase to heat up the line so to loosen and melt the ice.
Manual removal is also a commonly used process and can be done on energized lines, if required, to minimize outages. Oftentimes, ice can be manually removed on energized distribution lines up to 25 kV, and sub-transmission and transmission lines up to the voltage of 230 kV can be done with the line cleared and grounded.
The ice removal tool is a simple tool that has been conventionally used to manually remove a build-up of ice from overhead conductors. In general, manual ice removal is a labour-intensive procedure that requires many persons and/or a moving vehicle on the ground to pull, using and via fiberglass reinforced plastic (FRP) hotsticks and rope connected to the ice removal tool positioned on top of a power line, and the tool is basically “dragged” along the length of power line to break and shed built-up ice.
Upon reaching the end of a stretch of line and at each structure, the ice removal tool must be manually relocated to the next span by a qualified worker. The ice removal tool must come to a stop before the worker can climb the pole, and must not be pulled again until the worker is back on the ground. Manual ice removal would continue along the many stretches and spans in this fashion until all ice is removed. In our experience, depending on terrain and other environmental factors and the amount of ice buildup, a 10-person crew can on average de-ice roughly 1.6 kilometers of line per hour.
Evidently, manual ice removal is very labor intensive and time-consuming, and therefore expensive, notwithstanding slow, as the conditions and terrains are often very difficult. Past experience has also shown that with all the stops at each pole and the climbing there is a lot of idle manpower and machines.
Considering the importance of line de-icing and the obvious cost implications of the time and labour involved using conventional manual ice removal method, the attractiveness of an automated de-icing apparatus that can improve the practicality, reduce the costs, and increase the speed, of line de-icing has long been sought after.
For instance, since 1999, Manitoba Hydro has invested significant resources in researching and developing a robotic apparatus to try to develop such an automated tool. In 2010, Hydro-Quebec and BCTC received the Edison Award from the Edison Electric Institute in the International Affiliate category for their Line Scout robot that can be manually controlled (via remote) to traverse lines and clear obstacles (insulator strings, vibration dampers, aircraft warning markers, corona rings, etc.). The two sets of designs share some similarities, and while they may be useful for general line inspection, they are not suitable or equipped for rapid de-icing of power lines or conductors.
Notwithstanding, there have been description of devices that can travel (roll) along a conductor and carry special tools for ice removal such as spinning hammer means to hammer and break the ice off the conductor (as exemplified in Chinese Pat. No. 201174566Y); or blades, spikes, and scoops, to chip away ice from the conductor (as exemplified in Chinese Pat. No. 101557089A, Chinese Pat. No. 202817672U, and Chinese Pat. No. 202906344U). Whilst these mechanisms and approaches may in theory be capable of breaking ice off conductors, they can be relatively impractical under cold, windy, icy, and slippery, conditions, and the various tools described can also cause damage to conductors.
Other devices described in the prior art include the use of impact members to produce shock waves along a conductor to cause ice to break and fall from the conductor (as exemplified in Canadian Pat. No. 2,281,740 and Canadian Pat. No. 2,246,945) and the use of electromechanical vibrator to product vibrations on the conductor to break the ice from the conductor (as exemplified in U.S. Patent Application No. 2004/0065458 and International Patent Publication Number WO 02/47232). These are just stationary devices attached to a segment of conductor between pylons and are designed to only remove ice from that segment of conductor.
In view of the foregoing disadvantages of the prior art, it is therefore the primary objective of the present invention to provide novel apparatuses and methods for effective and efficient removal of extraneous matters, such as ice, frost, and snow, from power lines or conductors, that is less labor intensive and less time-consuming than conventional de-icing means.